Made options for formatting TypeScript documents

src/utils/typescript/typescript-formatting-options.ts

@@ -0,0 +1,192 @@
+import { DEFAULT_NEWLINE } from "@/utils/environment";
+
+/**
+ * Represents options for formatting TypeScript code as a string.
+ */
+export interface TypeScriptFormattingOptions {
+    /**
+     * The character(s) to use for a single indentation level.
+     *
+     * If not specified, the value of {@link DEFAULT_TAB} (4 spaces) will be used.
+     */
+    tab?: string;
+
+    /**
+     * The number of spaces to use for a single indentation level.
+     *
+     * If not specified, the value of {@link DEFAULT_TAB_SIZE} (`4`) will be used.
+     */
+    tabSize?: number;
+
+    /**
+     * The number of indentation levels to apply.
+     *
+     * If not specified, no indentation will be applied.
+     */
+    indent?: number;
+
+    /**
+     * The characters to use for line breaks.
+     *
+     * If not specified, the value of {@link DEFAULT_NEWLINE} (`\r\n` on Windows, `\n` on Unix) will be used.
+     */
+    newline?: string;
+
+    /**
+     * The preferred style for quoting strings in the formatted code.
+     *
+     * If not specified, the value of {@link DEFAULT_QUOTES} (double quotes, `"`) will be used.
+     */
+    preferredQuotes?: string;
+}
+
+/**
+ * The default string to use for a single indentation level.
+ */
+export const DEFAULT_TAB = "    ";
+
+/**
+ * The default number of spaces to use for a single indentation level.
+ */
+export const DEFAULT_TAB_SIZE = 4;
+
+/**
+ * The default style for quoting strings in the formatted code.
+ */
+export const DEFAULT_QUOTES = "\"";
+
+export { DEFAULT_NEWLINE, UNIX_NEWLINE, WINDOWS_NEWLINE } from "@/utils/environment";
+
+/**
+ * Returns the string to use for a single indentation level, based on the given formatting options.
+ *
+ * @param options - The formatting options to use. If not provided, default values will be used.
+ *
+ * @returns The string to use for a single indentation level.
+ */
+export function getTab(options?: TypeScriptFormattingOptions): string {
+    // If a specific tab character is specified, use it.
+    if (typeof options?.tab === "string") {
+        return options.tab;
+    }
+
+    // If a specific tab size is specified and it's not the same as the default, generate a new tab string from it.
+    if (typeof options?.tabSize === "number" && options.tabSize !== DEFAULT_TAB_SIZE) {
+        return createTab(options.tabSize);
+    }
+
+    // Otherwise, use the default tab string.
+    return DEFAULT_TAB;
+}
+
+/**
+ * Returns the indentation string to use based on the given formatting options.
+ *
+ * @param options - The formatting options to use. If not provided, default values will be used.
+ *
+ * @returns The indentation string to use.
+ */
+export function getIndentation(options?: TypeScriptFormattingOptions): string {
+    const tab = getTab(options);
+    return createIndentation(tab, options?.indent || 0);
+}
+
+/**
+ * Returns the string to use for line breaks based on the given formatting options.
+ *
+ * @param options - The formatting options to use. If not provided, default values will be used.
+ * @returns The string to use for line breaks.
+ */
+export function getNewline(options?: TypeScriptFormattingOptions): string {
+    // If a specific newline character sequence is specified, use it.
+    // Otherwise, use the default line break character sequence based on the current operating system.
+    return typeof options?.newline === "string" ? options.newline : DEFAULT_NEWLINE;
+}
+
+/**
+ * Returns the preferred style for quoting strings based on the given formatting options.
+ *
+ * @param options - The formatting options to use. If not provided, default values will be used.
+ *
+ * @returns The preferred style for quoting strings.
+ */
+export function getQuotes(options?: TypeScriptFormattingOptions): string {
+    // If a specific quote style is specified, use it.
+    // Otherwise, use the default quote string.
+    return typeof options?.preferredQuotes === "string" ? options.preferredQuotes : DEFAULT_QUOTES;
+}
+
+/**
+ * Returns a new set of formatting options with the indentation level incremented by the given amount.
+ *
+ * @param options - The formatting options to use as the starting point. If not provided, default values will be used.
+ * @param step - The number of indentation levels to add. Defaults to `1` if not provided.
+ *
+ * @returns A new set of formatting options with the incremented indentation level.
+ */
+export function incrementIndent(options?: TypeScriptFormattingOptions, step?: number): TypeScriptFormattingOptions {
+    const indent = (options?.indent || 0) + (step ?? 1);
+    return { ...options, indent };
+}
+
+/**
+ * A cache of previously generated tab strings, keyed by their length.
+ */
+const CACHED_TABS = new Map<number, string>([
+    [DEFAULT_TAB_SIZE, DEFAULT_TAB],
+]);
+
+/**
+ * Generates a string of spaces with the given width to use as an indentation level.
+ *
+ * @param tabSize - The number of spaces for a single indentation level.
+ *
+ * @returns The generated tab string.
+ */
+function createTab(tabSize: number): string {
+    const cachedTab = CACHED_TABS.get(tabSize);
+    if (cachedTab !== undefined) {
+        return cachedTab;
+    }
+
+    const generatedTab = " ".repeat(tabSize);
+    CACHED_TABS.set(tabSize, generatedTab);
+    return generatedTab;
+}
+
+/**
+ * A cache of previously generated indentation strings, keyed by the combination of their `tab` and `indent` values.
+ */
+const CACHED_INDENTATION = new Map<string, Map<number, string>>();
+
+/**
+ * Generates a string of spaces using the provided tab string and indent count.
+ *
+ * @param tab - The string to use for a single indentation level.
+ * @param indent - The number of indentation levels to apply.
+ *
+ * @returns The generated indentation string.
+ */
+function createIndentation(tab: string, indent: number): string {
+    if (!indent) {
+        return "";
+    }
+
+    if (indent === 1) {
+        return tab;
+    }
+
+    const cachedIndentationsByTab = CACHED_INDENTATION.get(tab) || new Map<number, string>();
+    if (!cachedIndentationsByTab.size) {
+        CACHED_INDENTATION.set(tab, cachedIndentationsByTab);
+    }
+
+    const cachedIndentation = cachedIndentationsByTab.get(indent);
+    if (cachedIndentation !== undefined) {
+        return cachedIndentation;
+    }
+
+    const generatedIndentation = tab.repeat(indent);
+    cachedIndentationsByTab.set(indent, generatedIndentation);
+    return generatedIndentation;
+}